This is the 3348th most frequent Korean word.
너머로
"너머로" means "beyond" or "over."
The word '너머로' is used here to indicate looking beyond a physical boundary, the window, to see the sky.
창문 너머로 푸른 하늘이 보입니다.
Beyond the window, the blue sky is visible.
'너머로' in this sentence demonstrates looking past a geographical landmark, the mountain, where the sun's activity is observable.
산 너머로 해가 저물고 있다.
Beyond the mountain, the sun is setting.
Here, '너머로' is used in a figurative sense to imply understanding emotions that remain behind a person's outward expression.